1. Field of the Invention
This invention relates to a distance measuring device, in particular, to a magnetostrictive distance measuring device.
2. Background Art
The basic principle is that a distance measuring element extends in longitudinal direction of the device along the distance to be measured and a signal generating position generator is moveable in longitudinal direction relative to it.
In a magnetostrictive distance measuring device, the basic principle of such a device is refined in so far, as a wave conductor made from an electrically conductive and also magnetizable material extends in measuring direction, the longitudinal direction of the device, in particular, in a slightly taunt state.
A magnet is connected with the component, whose position in longitudinal direction is to be measured, or monitored, and is being moved by this component in longitudinal direction of the wave conductor without contacting, but at a sufficiently small distance.
An electrical impulse induced into the wave conductor causes a mechanical wave as an interaction with the magnet, which propagated along the wave conductor from the position of the magnet, and which is detected with respect to its runtime by the processing electronics, which are mostly located at the end of the wave conductor, from which the longitudinal position of the magnet, and thus of the component to be monitored, is known relative to the wave conductor.
Since such distance measuring devices often have to be used in machinery, also in production machinery, they have to comply with numerous requirements, like e.g. protection of the measuring device against mechanical damages and contamination, in particular, against penetration of moisture into the processing electronics, maintaining the original tension of the wave conductor, shielding electromagnetic radiation of the processing electronics towards the outside and the inside, ease of assembly, and maintenance of the measuring device.
One the one hand, it is already known in this respect to receive the wave conductor in a supporting, but not overly dampening enclosure, and to use it as a wave conductor unit in this form.
On the other hand, it is already known to locate the wave conductor or the wave conductor unit in a protected manner in an interior of a circumferentially closed hollow tubular profile, which can be manufactured as an extruded profile in a cost effective manner.
Thus, the tubular profiles have to comply with different requirements depending on the intended use:                high stiffness against bending in lateral direction;        small space requirement, especially as a very flat tubular profile;        symmetrical shape of the interior cavity of the tube for variable use;        specific mounting method of the tubular profile relative to its environment;        rotatability of the tubular cross section, in particular, also in already assembled state, relative to the component carrying the profile;        particularly cost effective manufacture; and        possibility to place in an additional protective second housing.        
For this purpose, the outer contour, as well as the inner contour, of the profile had a defined shape. The inner contour was designed for receiving the wave conductor units, as well as the single or plural circuit boards, carrying the processing electronics. The conductor designs, in particular of the inner contour, had to allow for different technical outfitting. For high sealing requirements, where the flat placement of a cover with a flat gasket onto the front face of the profile was not sufficient, the front end areas of the profile had to be milled into a contour without a shoulder, into which a cover with an accordingly shaped protrusion, whose outer circumference had an annual groove for receiving an O-ring, could be inserted, what allowed for much improved sealing.
Without a shoulder in this context means that the respective interior contour has no concave or convex protrusions or indentations, whose curvature radius is so small that a sealing O-ring moved over it, is permanently damaged and loses its sealing capability.
This milling, however, was time consuming and difficult because of the 5 meter long profiles, in whose end areas these millings had to be performed.